This study was conducted to investigate the growth performance of lambs fed  sugar beet tops silage (SBTS) with concentrate feed mixture CFM. Forty growing male lambs (20 Frafra and 20 saidi weight 20.19 kg as average) were used in feeding trail. Animals were randomly divided into five similar groups according to their live body weight beside twenty mature rams (45 kg live body weight) were used in digestibility trails. Each groups were fed one of the following diet. (T1), CFM +Wheat Straw control, (T2) , CFM + SBTS supplemented with 0.25 urea /100 kg dry matter of silage un-chopped), (T3), CFM + SBTS supplemented with 0.25 urea /100 kg dry matter of silage chopped),  (T4), CFM + SBTS supplemented with 0.5 urea /100 kg dry matter of silage un-chopped),  (T5), CFM + SBTS supplemented with 0.5 urea /100 kg dry matter of silage chopped). CFM were offered as 3% of live body weight for all groups ,while roughages were fed ad lib. Control T1 had higher (P<0.05)  digestibility in CP, CF, EE and TDN compared with treatments containing ureated SBTS chopped or un-chopped, but diets ureated with 0.25% urea chopped or unchopped was better in digestibility than those ureated with 0.5% urea. Rations containing 0.25% urea chopped or un-chopped(T2 andT3) were the best (P<0.05) digestibility in OM, NFE and digestible crude protein (DCP) than rations T4,T5 and control. The values  of total nitrogen intake (TNI), fecal nitrogen (FN),urinary nitrogen(UN), total nitrogen excretion(TNE), nitrogen balance(NB) and  nitrogen absorption (NAB)  in control treatment lower (P<0.05) than other treatments. Total gain and daily gain were reicorded by the rations contain SBTS( U .0250% ) higher than rations contain SBTS (U.0.5%) and control ration . This diferences were insignificant. The significant(P<0.05)  higher DM and TDN consumed by lambs fed control ration (T1),but feed intake as DCP has lower than other treatments . Lambs fed T2 and  T3, showed the best conversion as DM and TDN, compared with those fed (T1),(T4) and(T5). Therefore, the  lowest feed cost and the best weight gain equal the best revenue and better economic efficiency which showed by lambs fed diets containing ureated sugar beet tops T2 flowed by T3, T4, T5 and T1.